ci: simplify PHPCS workflow and update PHPUnit version constraints

Author: ajaydsouza

.github/workflows/cs.yml

@@ -30,24 +30,19 @@ jobs:
           tools: cs2pr
           coverage: none
 
-      - name: 'Composer: set up PHPCS dependencies'
-        run: |
-          composer require --no-update squizlabs/php_codesniffer wp-coding-standards/wpcs phpcompatibility/phpcompatibility-wp dealerdirect/phpcodesniffer-composer-installer
-          composer config allow-plugins.dealerdirect/phpcodesniffer-composer-installer true
-
       # Install dependencies and handle caching in one go.
       # @link https://github.com/marketplace/actions/install-composer-dependencies
       - name: Install Composer dependencies
         uses: "ramsey/composer-install@v3"
 
       - name: 'Run Composer Update'
         run: |
-          composer update
+          composer update -W --ignore-platform-req=php
 
       # Check the code-style consistency of the PHP files.
       - name: Check PHP code style
         continue-on-error: true
         run: vendor/bin/phpcs --report-full --report-checkstyle=./phpcs-report.xml
 
       - name: Show PHPCS results in PR
-        run: cs2pr --graceful-warnings ./phpcs-report.xml
+        run: cs2pr --graceful-warnings ./phpcs-report.xml

composer.json

@@ -30,7 +30,7 @@
         "dealerdirect/phpcodesniffer-composer-installer": "^1",
         "phpcompatibility/phpcompatibility-wp": "^2",
         "yoast/phpunit-polyfills": "^3",
-        "phpunit/phpunit": "^7.5 || ^8 || ^9 || ^10 || ^11 || ^12"
+        "phpunit/phpunit": "^9 || ^10 || ^11 || ^12"
     },
     "config": {
         "allow-plugins": {